This topic
describes the z/OS terminology that is required
when using WebSphere® Application Server for z/OS®.
In WebSphere Application
Server for z/OS,
the functional component on which applications run is a server.
The following diagram shows a z/OS server running two J2EE applications:

Servers comprise address spaces that
run code. A z/OS server has
two types of address space:
controllers and
servants:
The following types of
server can be present on a z/OS system:
- Unmanaged (standalone) application server
- This application
server is set up during standalone configuration
to host your J2EE applications.
- Managed
(Network Deployment) application server
- This application server
is set up during Network Deployment configuration
to host your J2EE applications.
- Location
service daemon
- This server is the initial point of contact
for client requests
in either standalone or Network Deployment configuration. The location
service daemon is a specialized server that have no servants.
- JMS server
- This server hosts the JMS
function in WebSphere Application
Server for z/OS, which controls the MQ broker and queue
manager in either standalone or Network Deployment configuration. The
JMS server no longer exists as in previous versions of WebSphere Application
Server for z/OS. Its function has been replaced with service
integration busses.
- Deployment manager
- This is a specialized application server that hosts the administrative
console application (it hosts only administrative applications) and
provides cell-level administrative function in a Network Deployment
configuration. The administrative console application administers
servers (grouped into nodes) on many different systems. The deployment
manager is the sole occupant of its own node. It does not need a node
agent because there are no application servers in the node, and a
cell can have only one deployment manager.
Note: The version of the
administrative console application that runs in the deployment manager
is designed to manage multi-node environments, whereas the version
of the administrative console application that runs in the standalone
application server is for single node environments only.
- Node agent
- A node agent provides node-level
administrative function in a
Network Deployment configuration. A node agent is a specialized server
that has no servants.
A node can contain servers
that are part of a cluster. The cluster
can span nodes if all the involved nodes are in the same cell.
- cluster
- A cluster is a logical grouping
of like-configured servers.
Clusters
exist to promote scalability and availability. Workload balancing
occurs across the servers in a cluster. Clusters allow you to partition
workloads into separate servers while still referring to them as a
single unit. Clustering is typically applied to a multinode cell,
where each node is configured on a separate system and the cluster
has a member (server) on each node. Client requests are distributed
among the cluster members based on workload manager decisions.
Note: If
you intend your cluster to span multiple systems in a sysplex, you
might need to set up a shared HFS.
- node
- A node is a logical collection of servers on one particular z/OS system.
- A node belongs to one cell. The cell to which a node
belongs can
span several systems, but the node must remain within a single z/OS system.
- A z/OS system can contain multiple WebSphere Application
Server for z/OS nodes that belong to the same or different
cells.
- cell
- A cell is
a logical collection of WebSphere Application
Server for z/OS nodes that are administered together. The
cell is the largest unit of organization.
- Nodes
that comprise a cell can reside on systems in the same sysplex,
differing sysplexes, on the same z/OS monoplex,
or on differing systems entirely. A cell that consists of nodes on
differing systems or sysplexes is called a heterogeneous cell.
- A z/OS sysplex or monoplex can contain multiple WebSphere Application Server for z/OS cells.
- Different cells can have nodes on the same systems, although a
given node can be a member of only one cell.
- There are two
kinds of WebSphere Application Server
for z/OS cell:
- A standalone cell
consists of a single node. Due to administrative constraints, this
node should have only a single application server in it.
- A Network
Deployment cell consists of a deployment manager node, which
is responsible for cell-wide administrative tasks, and any number
of federated nodes. Each federated node contains a node agent, which
handles communication with the cell's deployment manager, and any
number of application servers.
- administrative
agent
- An administrative agent provides a single interface
to administer
multiple unfederated WebSphere Application Server
for z/OS nodes in environments such as development,
unit test, or that portion of a server farm that resides on a single
machine.
- secure proxy server
- A
secure proxy server can be installed in the demilitarized zone
(DMZ) to reduce the security risk that might occur if you choose to
install an application server in the DMZ to host a proxy server.
Every element of the configuration (servers,
clusters, nodes and
cells) has both a long and short name:
- Server
name
- This is the long name used in the HFS path, and the principal
name by which the server is known to WebSphere Application
Server for z/OS. It is used to identify the server through
the administrative console and scripting. It is a mixed case name
and longer than 8 characters.
- Server short
name
- This is the platform-specific native alias, and the principal
name by which the server is known to z/OS.
It is used to identify the server to underlying z/OS facilities,
such as the Security Server, Job Entry Subsystem (JES), WLM and Application
Response Management (ARM). For example, the server short name is used
as the MVS JOBNAME.
- Cluster
short name
- This is used as the WLM application environment
name.
The following diagram illustrates
the interaction between servers,
clusters, nodes and cells. It shows various configurations that you
can set up in a Network Deployment sysplex:

Cells 1
and 3 illustrate Network Deployment configuration cells. Cell 2 is
a standalone configuration cell.
Node assignments can vary according
to your requirements. The deployment
manager node can exist on one system while other nodes that have been
federated into the deployment manager can exist on different systems.
Such a configured cell comprising differing machines or operating
systems is called a heterogeneous cell and expands the
possible topologies you can consider for your network deployment.